Method of and apparatus for radioreception



Nov. 26, 1929. w. M. BRUCE, JR

METHOD OF AND APPARATUS FOR RADIO RECEPTION Filed Feb. 17. 1926 2Sheets-Sheet wuemtoz M 4 WV Nov. 26, 1929. 1 w. M. BRUCE. JR 1,737,407

METHOD OF AND APPARATUS FOR RADIO RECEPTION Filed Feb. 17, 1926 2Sheets-Sheet 2 Q Q E in f ail D I 1 mm m m u mlioz P'atented Nov. 26,1929 WILLIAM M, BRUCE, an, on SPRINGFIELD, orrro METHOD OF AND APPARATUSFOR B-NADIORECEPTION Application filed February 17, 1926. Serial No.88,782.

My invention relates to methods and apparatus for radio receptions andit more particularly relates to methods and means for extending the bandof radio frequencies on which broad-casting so called can be receivedand also to materially amplify the reception of radio broad-casting.

In the present state of the art broad-castingis limited to a band offrequencies ranging from approximately 200 to 600 meters and it has notbeen found practical with the present apparatus in use to receive andamplify the broad-casting on different wave lengths particularly .thoseshorter wave lengths or higher frequencies.

Also in the present state of the art receiving sets for broad-castingespecially those of higher amplifications employ several stages of radioamplification as well as a seriesv of stages of audio amplification. For reasons number of audio amplification as the frequencies areincreased the stages of radio amplifications become more difiicult. Inmy improved system many of these difficulties are overcome and it ismade possible to receive and amplify radio messages and programs on thehigher frequencies and shorter wave lengths and also to further amplifysuch messages on the present band of broad-casting frequencies.

Experiments seem to have demonstrated that the shorter wave lengths orhigher frequencies when modulated byvoice or otherwise are capable ofbeing transmitted to longer distances and with less initial power orwattage than the longer wave length or lower frequencies. Wave lengthsfrom around to meters have been employed successfully in trans-Atlantictransmissions and for a distance of approximately one half thecircumference of the globe, where the longer wave lengths and lower freuencies have not been successful; besides suc modified short wave radiofrequencies can not be received on the present receiving apparatus ingeneral use.

In carrying out my invention I make use of a local generated frequencyadapted to be received on an ordinary receiving set or upon a recelvingset adapted to the particular frequency determined upon to be generatedat the local station and I modulate these locally produced frequenciesor oscillations by the incoming signals of a different wave length orfrequency. These local frequencies thus produced can be detected andamplified to the desired degree by the usual apparatus now in use and ifdesired can be further increased and amplified by employing another setof oscillations locally produced to another receivlng apparatus and thiscan be continued until the amplification reaches a volume, not possibleby the present methods.

In the accompanying drawings, Fig. 1 is a diagrammatic view of anapparatus em bodylng my invention. Fig. 2 is a detailed view relatingparticularly to the local oscillator or the means for producing thelocal oscillations. Fig. 3 is a diagrammatic View showing the means forextending the range of amplification by the use of several intermediateoscillators for generating local oscillations or frequencies.

Referring to Fig. 1, the apparatus may be said to include threeprincipal features: 1) a detecting apparatus for'any desired band offrequencies, preferable of lower wave lengths than are now used in theusual broad-casting, say from '25 to 100 meters; (2) an oscillator ordevice for producing radio frequency oscillations having a frequencydifierent from the incoming signals, and if it is to be used with theusual broad-casting receiving sets it would have a frequency within aband of say from 200 to 600 meters which the receiving apparatus is bestadapted for; for instance, it could have an oscillation which wouldproduce frequencies of say 800 meters. (3) This represents the othersection of the apparatus which may be an ordinary receiving set with theusual detector and amplifiers. In this Fig. 1

0 represents an aerial and b a thermionic tube mary p of an audiofrequency transformer t where they are impressed upon the locallygenerated radio frequency produced by the oscillator 2. As theseoscillator circuits are well known it is perhaps unnecessary to'describethem in detail.

The locally produced oscillations modified by the incoming signalsrelayed by the detector b of the detecting apparatus 1 are thentransmitted to the receiving apparatus 3 which I have illustrated as ofthe two tube regenerative type, tube 6 being a detector and the tube ban amplifying tube with adjustable inductance, such as the ordinaryvariometers 'v and 1 I have shown in the section 3 of this View aconnection to the aerial a which may be employed if desired and there isprovided in connection with the aerial a, a double-throw switch 8 sothat in one position the aerial would be connected to section 1 of thereceiving apparatus and when in the other position it would be connectedto section 3. By this arrangement when the switch is in the positionshown in full lines, the radio reception would be through section 1' forshort wave lengths and detector b and the usual circuits for thisapparatus and the incoming signal would, through the audio transformer25, modify the locally generated high frequencies oscillations'whichwould in turn be picked up by the detector 6 of section 3 of theapparatus and there be amplified and received on the usual receiver 1'.

In the event it was desired to receive messages impressed on longer wavelengths or lower frequencies, for instance those in the presentbroad-casting band, by throwing the switch to the position shown indotted lines the detector 1 and the oscillator 2 would be cutout andmessages on the longer wave lengths be received directly on thereceiving section 3 in a normal manner.

In Fig. 3 I have shown a method of increasing the amplification by theuse of a plurality of oscillators producing or generating local radiofrequencies or oscillations and in this Figure 3, 1 represents thedetector apparatus, 2 the first oscillator modulated thereby, 3 areceiving set, 4 a second oscillator, and 5 a second receiving set. Inthis figure there are shown in the preliminary detecting circuits adetector and two stages of audio frequency amplifications. Theoscillator 2 is the same as that shown in Fig. 1 and the receiving setis shown with three stages of radio frequency amplification and twostages of audio frequency amplification; at 4 is shown a secondoscillator the same as at 2 and the received messages on the receivingset 3 are transmitted to the oscillator 4: and modulates the frequenciesproduced by the second oscillator' l which are in turn transmitted toand received by the second receiving apparatus 5. In this way itispossible to use a very large number the usual receiving sets.

'6 and b are amplifying tubes connected by radio frequency transformersto the detector circuit and transmitted from the plate of the secondamplifying-tube b to the oscillator tube 6 Any well known circuit may beemployed with the usual inductance and capacity to produce oscillationswhich will be modulated by the incoming signals from the plate circuitof'the tube 6 through the audio frequency transformer t and will in turnbe picked up by the detector tube 1)? of the receiving set 3 where theymay be amplified by the radio frequency transformer and tubes b? and band thence further amplified by the tubesb and Z)". From the platecircuit of the tube 5 the audio frequencies would be impressed upon andmodulate an additional set of oscillations produced bythe oscillator 4,

which in turn, would be picked up by the detector tubes of the receivingset 5 and ampliradio frequency and audio frequency amplification andfinally received by the receiver 1.

I have demonstrated in actual use that by a detector set of two tubes i.e., a detector fied in the usual way by various stages of and one stageof audio frequency amplification, signals or messages can be picked upon high frequencies, say 25 to 60 meters in length, and can besuccessfully used to modulate oscillations locally produced of say 300meters and can be impressed upon an ordinary two or three tuberegenerative circuit with much less interference and much greater volumethan when an ordinary receiving set of five or six tubes is employed. Ithas been this character broad-casting on high frequencies of the orderof 41 and 61 meters can be received on a three tube regenerative setthrough a detector and local oscillator producing frequencies of theorder of 300 meters with greater definition and volume and lessinterference than can be obtained on the present broad-casting band withthe usual receiving sets having a detector and several stages of radioand audio frequency amplification.

By the use of this invention it Will be seen that receiving sets-now inuse that are limited to a band of oscillations from say 200 to 600meters can be employed with a band of much higher frequencies, by theaddition of the detector set for, high frequencies arranged to modulatelocally produced oscillatlons having a frequency within the band ofdemonstrated that-by the use of a device of It is also possible by thissystem to use a plurality of receiving sets at any desired frequencywith a larger range of amplifications and with a minimum amount ofdisturbance than is possible with the present method of reception.

It is possible to amplify various wireless signals either telephonic ortelegraphic or of continuous wave or damped wave transmission when radiofrequencies are transmitted to the local oscillator as in the case oftelegraph signals a radio frequency transformer would be substituted forthe audio frequency transformer between the first receiver and theoscillator.

Having thus described my invention, I claim:

1. A receiving apparatus for wireless signals comprising an aerial, adetector for high frequency oscillations, an oscillator, and means forconnecting said detector to said oscillator so that the modulated highfrequency oscillations from the detector will modulate the oscillationsof said oscillator, a receiving device embodying a detector andamplifier to detect and amplify the modulations of the localoscillations, and means whereby the aerial may be connected to one ofthese detectors and disconnected from the other detector.

2. A receiving apparatus for wireless reception embodying a plurality ofdetecting and amplifying devices and an oscillator between said devicesand connected thereto so that the audio modulations of the first de-"tector will modulate the'oscillations of said oscillator and saidmodified oscillations be detected and amplified for reception by thesecond detecting and amplifying device, and aerial connections, withmeans for connecting and disconnecting either of said detecting deviceswith the aerial.

3. In a receiving apparatus for wireless reception, a plurality ofreceiving devices and an oscillator, means for coupling said oscillatorto two of said receiving devices so that the detected signal modulationsin the output circuit of one receiver will modulate the locally producedoscillations of said oscillator and the other receiver will detect andamplify the locally produced oscillations, an aerial connected to theinput circuit of each receiving device and switch means in the input ofthe second receiving device adapted to disconnect said input from itsaerial and connect it to the output of said oscillator.

4. The combination with a radio receiving set arranged to detect andamplify signals formed as modulations upon a relatively low frequencycarrier wave, of an attachment therefor comprising a detector to detectsignals formed as modulations upon a relatively high frequency carrierwave, said frequency being too high for adequate reception by said radioreceiving set, and an oscillator to produce oscillations of a frequencywithin the receptive capacity of said radio receiving set, and means forimpressing the modulations detected by the detector, upon theoscillations produced by the oscillator, and means for feeding saidmodulated oscillations to said radio receiving set.

5. The combination with a radio receiving set arranged to detect andamplify signals formed as modulations upon a relatively low frequencycarrier wave, of an attachment therefor comprising a detector to detectsignals formed as modulations upon a relatively high frequency carrierwave, said frequency being too high for adequate reception by said radioreceiving set, said attachment also comprising means for producingoscillations at a frequency within the range of said radio receivingset, means for impressing the detected modulations upon saidoscillations, and means for feeding the said'modulated oscillations tosaid radio receiving set. a

In testimony whereof, I have hereunto set my hand this 11th day ofFebruary, 1926.

WILLIAM' M. BRUCE, JR.

